A simulation model predicting effects of social, physical, and nutritional environments on pig food intake and performance was extended to account for individual variation. The goal was to investigate the effects of between animal variation on the performance of a population of growing pigs. It has been previously suggested that pigs with a leaner, more modern genotype may be less able to cope when exposed to social stressors. Similarly, it has been suggested that a pig’s position within the social hierarchy may affect ability to cope with social stressors. In the model, it was assumed that larger, more dominant pigs would be better able to cope when exposed to social stressors. The model showed that increasing initial body weight variation and the number of stressors increased the variation in pig performance. In commercial operations, where population variation may affect the profitability of the enterprise, this model may be an important practical consideration. The way a stressor effects performance determines whether the mean population response and the average individual response will be the same. If all the pigs in a group were affected at the same intensity by the stressor, then predicted mean and average individual responses would be the same. If the intensity of the stressor affected each pig differently, then differences between the individual and mean population responses would be predicted. Variation in initial body weight and social stressors were better determinants of the variation in growth response than a variation in growth potential was when pigs were housed in conditions similar to those found in commercial environments. In conclusion, decreasing the variation in initial body weight and improving the ability of pigs to cope may be a better for improving pig performance than selecting for increased growth potential alone.